Drum magazine for firearm

Abstract

A detachable magazine for storing and delivering ammunition to a firearm having a magazine well. The magazine has a body with a column adapted for insertion into the magazine well. The column has a passage for transmitting ammunition to the firearm. The body includes a drum housing defining a substantially cylindrical chamber communicating with the column passage. A first sprocket element is rotatably received in the chamber and has a serrated periphery, with each serration adapted to receive an ammunition cartridge. A second sprocket element is rotatably received in the chamber, and is concentric with the first sprocket element, having a serrated periphery with each serration adapted to receive an ammunition cartridge. A spring element is connected to at least one of the sprocket elements, and operates to rotatably bias the sprocket elements to transmit cartridges from the drum chamber to the column passage. The magazine may have a pair of drums, and the sprockets may be tapered, to facilitate feeding of tapered cartridges. The magazine may include a counter to indicate the quantity of ammunition consumed or remaining. The magazine may include the ability to power and de-power spring motor.

1. A detachable magazine for storing and delivering ammunition to a firearm having a magazine well, the magazine comprising:
 a body having a column adapted for insertion into the magazine well; 
 the column defining a passage for transmitting ammunition to the firearm; 
 the column having a width selected to receive a double stack of ammunition; 
 the body including a drum housing defining a substantially cylindrical chamber communicating with the column passage; 
 a first sprocket element rotatably received in the chamber and having a serrated periphery with each serration adapted to receive an ammunition cartridge; 
 a second sprocket element rotatably received in the chamber, and concentric with the first sprocket element, and having a serrated periphery with each serration adapted to receive an ammunition cartridge; 
 a spring element operably connected to at least one of the sprocket elements, and operable to rotatably bias the sprocket elements to transmit cartridges from the drum chamber to the column passage; and 
 wherein the serrations define centerlines that converge to a common point to the rear of the magazine, such that stored cartridges are arranged with their forward tips splayed outward from an axis defined by the sprocket elements. 
 
   
   
     2. The magazine of  claim 1  wherein the spring is selectably engaged to the sprocket elements, so that the magazine may be loaded without substantial biasing force resisting the loading. 
   
   
     3. The magazine of  claim 1  wherein each sprocket element has spaced apart sprocket discs each defining serrations. 
   
   
     4. The magazine of  claim 3  wherein one of the discs has a smaller periphery than the other, such that cartridges received in the serrations will define centerlines that are angularly offset from each other. 
   
   
     5. The magazine of  claim 4  wherein the serrations of each disc are arcs defining centers, the arc centers of each disc being arrayed in a circle having a selected diameter, the selected diameter for the first disc being smaller than the selected diameter of the second disc. 
   
   
     6. The magazine of  claim 5  wherein the arcs of the first disc have a smaller radius than the arcs of the second disc. 
   
   
     7. The magazine of  claim 1  including an ammunition counter attached to the body and responsive to the passage of each cartridge, and having an indicator indicating the quantity of cartridges passed. 
   
   
     8. A detachable magazine for storing and delivering ammunition to a firearm, the magazine comprising:
 a body having a conduit defining a passage for transmitting ammunition to the firearm; 
 the body including a first drum housing and a second drum housing, each defining a generally cylindrical chamber communicating with the conduit passage; 
 each drum housing containing a first sprocket element rotatably received in the chamber and having a serrated periphery with each serration adapted to receive an ammunition cartridge; 
 each drum housing containing a second sprocket element rotatably received in the chamber, and concentric with the first sprocket element, and having a serrated periphery with each serration adapted to receive an ammunition cartridge; 
 each sprocket element having spaced apart first and second sprocket discs each defining serrations; and 
 each drum housing containing a spring element operably connected to at least one of the sprocket elements, and operable to rotatably bias the sprocket elements to transmit cartridges from the drum chamber to the conduit passage. 
 
   
   
     9. The magazine of  claim 8  wherein each spring is selectably engaged to the sprocket elements, so that the magazine may be loaded without substantial biasing force resisting the loading. 
   
   
     10. The magazine of  claim 8  wherein each drum is slightly tapered to define a frustoconical chamber. 
   
   
     11. The magazine of  claim 8  wherein one of the discs has a smaller periphery than the other, such that cartridges received in the serrations will define centerlines that converge. 
   
   
     12. The magazine of  claim 11  wherein the serrations of each disc are arcs defining centers, the arc centers of each disc being arrayed in a circle having a selected circle diameter, the selected circle diameter for the first disc being larger than the selected diameter of the second disc. 
   
   
     13. The magazine of  claim 12  wherein the arcs of the first disc have a smaller radius than the arcs of the second disc. 
   
   
     14. The magazine of  claim 8  including an ammunition counter attached to the body and responsive to the passage of each cartridge, and having an indicator indicating the quantity of cartridges passed. 
   
   
     15. The magazine of  claim 8  wherein the drums are on opposite sides of the conduit, and the drums have peripheral apertures communicating with the conduit, and wherein the apertures face each other. 
   
   
     16. A detachable magazine for storing and delivering ammunition to a firearm having a magazine well, the magazine comprising:
 a body having a column adapted for insertion into the magazine well; 
 the column defining a passage for transmitting ammunition to the firearm; 
 the body including a drum housing defining a substantially cylindrical chamber communicating with the column passage; 
 a first sprocket element rotatably received in the chamber and having a serrated periphery with each serration adapted to receive an ammunition cartridge; 
 a second sprocket element rotatably received in the chamber, and concentric with the first sprocket element, and having a serrated periphery with each serration adapted to receive an ammunition cartridge; 
 the serrations configured such that stored cartridges are arranged with their forward tips splayed outward from an axis defined by the sprocket elements; and 
 a spring element operably connected to at least one of the sprocket elements, and operable to rotatably bias the sprocket elements to transmit cartridges from the drum chamber to the column passage. 
 
   
   
     17. The magazine of  claim 16  wherein each sprocket element has spaced apart front and rear sprocket discs each defining serrations, and wherein the forward one of the discs supporting forward portions of each cartridge has a larger periphery than the rear sprocket disc. 
   
   
     18. The magazine of  claim 17  wherein the arcs of the forward disc have a smaller radius than the arcs of the second disc. 
   
   
     19. The magazine of  claim 16  wherein the serrations define centerlines that converge to a common point to the rear of the magazine. 
   
   
     20. The magazine of  claim 16  wherein the serrations of each disc are arcs defining centers, the arc centers of each disc being arrayed in a circle having a selected diameter, the selected diameter for the first disc being smaller than the selected diameter of the second disc. 
   
   
     21. The magazine of  claim 16  including a pair of drums on opposite sides of the column. 
   
   
     22. The magazine of  claim 21  wherein each drum housing includes rotatable first and second sprocket elements defining an axis of rotation, and wherein the axes of rotation are parallel. 
   
   
     23. The magazine of  claim 21  wherein each drum housing includes a forward housing panel and a rear housing panel, and wherein forward housing panels are coplanar. 
   
   
     24. The magazine of  claim 21  wherein each drum housing includes a forward housing panel and a rear housing panel, and wherein rear housing panels are coplanar. 
   
   
     25. The magazine of  claim 21  wherein each drum housing has a straight cylindrical peripheral sidewall.